Big noise in sedan with one delayed going over states (9)
I believe the answer is:
charivari
'big noise' is the definition.
(type of parade involving making loud noises)
I don't understand the remainder of the clue.
(Other definitions for charivari that I've seen before include "uproar" , "Mock serenade" , "Noisy welcome" , "Hubbub" , "cacophony" .)